Answer:
If you combine load cases in action categories, you can define the behavior of the load cases within an action category in the Actions tab.Simultaneously
All load cases of the action can be combined as required. They can occur in a combination simultaneously, but this does not always happen.
Alternatively
Only one of the load cases of the action can be effective (for example, wind from different directions).
Differently
You can define differentiated relations between the load cases in an action. If you select this option, an additional column appears in the Load Cases in Action section of the dialog box. In this dialog box, the load cases can be assigned to a group so that they are mutually exclusive (as when they are acting Alternatively). You can select the number of the group from the list.
